The present invention relates to a multi-layer, parallel lay, coreless wire rope.
Multi-layer, parallel lay, coreless wire rope configurations exhibit greater resistance to crushing, are more stable and have longer rope life than multi-layer, parallel lay wire ropes having a core strand. However, there are certain undesirable features of coreless wire ropes of designs similar to those set forth in U.S. Pat. No. 3,181,291.
Such prior art ropes have inherent disadvantages. The three strand interior rope introduces a stiffness factor that differs greatly from the stiffness factor of the outer rope six strands. This difference can, under certain operating conditions, cause the interior rope to expand in an area or "pop" and the exterior rope to expand overall or "birdcage." This difference in stiffness factors resists any attempts at modifying the interior rope three strand design or configuration to produce a more flexible interior rope. The six exterior strands are minimal in number and do not provide sufficient outside wire surface area for optimum abrasion resistance and wire contact stress distribution.
Further, due to the component strand diameter differences, the ropes lack uniformity between strands and have less resistance to abrasion, bending fatigue, crushing and bearing stresses.
Accordingly, it is an object of the present invention to provide a multi-layer, coreless, parallel-lay wire rope that has improved stability, strength and rope life.